The Doctrine of the Trinity

A pertinent question for the early church was Jesus’ relationship to God the Father and the Holy Spirit. Establishing any cogent account of God’s essence needed textual justification which arose out of the apostles’s experiences with the risen Christ. Out of these texts the early church fathers developed more precise theological language to supplement how Scripture speaks of the relationship between the Father, Son (or Logos), and Holy Spirit. After all, the Bible is not foremost a treatise in systematic theology (although there are echoes of this throughout); rather, it is primarily a record of God’s covenant faithfulness to His people Israel and the greater world written by those who experienced it. The early Church fathers are largely responsible for the terms and language used throughout Church history to unpack and explain concepts conveyed in Scripture, and the Trinity is no exception (1). The task of creating this language proved to be a balancing act rejecting both the extremes of modalism (or Sabellianism) and Arianism. In this way, arguing for the Trinity needed both scriptural exegesis and theological justification.

As Philip Cary has argued, Trinitarian doctrine rests upon seven key propositions which are simple enough to comprehend in themselves but taken together form a “distinctive logic” which Christians have wrestled with for centuries:

  1. The Father is God.
  2. The Son is God.
  3. The Holy Spirit is God.
  4. The Father is not the Son.
  5. The Son is not the Holy Spirit.
  6. The Holy Spirit is not the Father.
  7. There is only one God. (2)

The early church fathers were committed to the belief in one God, but they believed the apostles made clear distinctions between different members of the Godhead. In most heresies these convictions held (or, hold) true as well. The modalist and Arian accounts of God attempted to account for God’s oneness while maintaining the distinctions between the Father, Son, and Holy Spirit. The modalists argued that there is one person within God, and the Father, Son, and Holy Spirit are merely varying modes of being this one God assumes. At some points God is the Son, and at other points God is the Father. In this way, the modalists conflated the members of the Trinity by reducing God to a single person without any economic interaction between distinct members. Oneness Pentecostals today maintain this position.

The problem with this view is that it disregards the divergences between the members of the Trinity. There are several passages within the New Testament that show varying actions amongst the Trinity which renders the notion that these are all simply one being manifesting in different forms absurd. For example, if modalism is true, then Jesus would have been praying to himself on the Mount of Olives which is where he distinguishes between his own will and the Father’s will (Luke 22:41-42) (3). Further, Matthew 3 records Jesus’ baptism, and in verses 16-17 the Spirit of God comes to rest upon Jesus while God’s voice declares, “This is my beloved Son, with whom I am well pleased.” Modalism cannot account for these distinct acts while maintaining that they are the same actions of one person because God would then have to change mode of being from the Son, to the Spirit, to the Father, and then back to the Son. Jesus would have been assumed back into heaven only to descend again as the Spirit, and then he would have to retreat back into heaven to proclaim Jesus as his own Son which is absurd.

Contrary to modalism, the Arians’ fault was to divide the persons of the Trinity to the point of total separation between the members. Arius was committed to God’s absolute oneness and divine impassibility (or inability for God to undergo change), so he argued that there is one person within God, the Father, and that the Son is merely a created being (albeit a supreme, even divine-like, created being). In other words, there was a time when Christ was not, so the Son had a beginning unlike the Father who has no beginning (4). As Arius himself wrote, “But we speak thus inasmuch as [the Son] is neither part of God nor from any substratum [(or common substance with God)]” (5). Therefore, the Logos of God is not God himself but is more like a super-creature. The Arians appealed to a number of biblical texts like Luke 2:52, Matthew 16:13, and Mark 6:38 where it states Jesus grew in wisdom, inquired of people, and lacked knowledge, respectively. Today, Jehovah’s Witnesses hold to this position.

In response to the Arians, Athanasius argued that if Christ was not God in the flesh but was rather some sort of divine creature mediating between God and creation, then Christ could not in himself impart salvation to humanity. He argued, “[I]f the properties of the flesh had not been reckoned to the Logos, humanity would not have been completely liberated from them” (6). In other words, the Logos had to become flesh or else Christ could not redeem the flesh. Humanity’s iniquities and sins are transposed upon him in the crucifixion and his righteousness is imputed to humanity (7). Therefore, Athanasius emphasized that one should not shy away from speaking of Christ’s human characteristics such as growing, learning, receiving, or suffering because all of these things occur in reference to the flesh while the Logos itself remains impassible, or unchanging.

Apart from Athanasius’ defense, the apostles also emphasized the equality between God the Father and God the Son in their divinity. In formulating a Christian Shema, Paul wrote, “[Y]et for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist” (1 Cor 8:6). The term, “Lord,” in the Greek is, “Kryos,” which is how the Septuagint translated the divine name YHWH. Therefore, the Jewish conviction of there only existing one God coupled with the name of YHWH being attributed to Christ leads to the conclusion that the New Testament writers both believed in one God yet thought of Christ as God.

Further, the apostles attributed actions to Jesus which were reserved for God alone. It was the Jewish conviction that only God could create (Gen 1-2, Isa 44:24), forgive sins (Mic 7:18, Mk 2:7), and change hearts (Jer 31:33, 1 Kgs 8:58). Throughout the New Testament, the apostles took these themes of creation, forgiveness, and sanctification and conveyed them through Jesus. For example, John (similarly to Paul in 1 Corinthians 8:6) attributes creative power to Jesus as God’s Word (Jn 1:3). God the Father creates all things yet he does so via his Word which became flesh. Not only does God create, but He also has sovereignty over the forces of nature (Job 38-41) which Jesus also demonstrates when these forces of nature yield to Him (Mat 8:23-27). Also, like the Father, Jesus declared he had the authority to forgive sins (Mk 2:8-12) which he did openly (Lk 23:42-43), and the apostle Paul believed in Christ’s ability to change hearts (2 Cor 3:3, 5:17).

For the early church fathers it was clear the New Testament presented the Father, Son, and Holy Spirit as distinct characters who are all somehow God, but Scripture offered no technical theological language for speaking of these relationships. If Scripture was the content for the early church’s theology, the fathers needed to produce the labels. Out of this need for systematizing biblical theology the church fathers introduced terms like, “homoousios,” (or, “same essence, or substance”) and “hypostasis,” (or, “person”) to express the threeness and the oneness of the Trinity. In the same way that Athanasius distinguished between Christ’s characteristics in regards to his humanity and his divinity, the Church distinguished between the threeness and the oneness in regards to the Trinity’s essence (“ousia“) and persons (“hypostases“) in order to avoid equivocation and speaking contrarily. The Athanasian Creed speaks of it as, “[N]either confusing the persons nor dividing the substance.” In other words, any coherent formulation of the Trinity must maintain the essential boundaries the Creed lays out.

In accordance with God’s oneness, theologians like Gregory of Nyssa reiterated the concept that the Trinity is truly homoousios, or of the same substance. He argued, “[B]eing infinite, incomprehensible, uncreated, uncircumscribed by any place and all such qualities, there is no variation in the life-giving nature – of Father, Son, and Holy Spirit… the communion contemplated in them is in a way continuous and inseparable” (8). In other words, one cannot divide the Godhead by introducing some sort of substance or element foreign to the singleness found within the Trinity itself. If a person divides the Trinity into distinct substances then there cannot be any oneness within the Trinity and one has instead advocated for three gods. In this way there can be no variation between the substance of God’s members. The Athanasian Creed uses the words, “begotten of the Father alone,” to describe the Son’s relation of origin to the Father, and, “neither made nor created nor begotten, but proceeding,” to describe the Spirit’s relation of origin. This begottenness and proceeding is so closely intertwined within the Trinity that it does not produce three gods nor does it substantiate a Unitarian conception of God with the Son and the Spirit being mere lesser creations. Whatever is the Father’s mode of being will also include the Son and likewise the Holy Spirit (9). This close relation does not merely include God’s mode of being but also God’s actions.

When a Christian trusts in Christ for salvation, she does not portion off the Godhead in faith. Whoever receives the Son receives the Father and the Spirit also (10). This interconnectivity is so closely knit that Gregory compares it to light. The color spectrum has no intervening space yet it does not mix the variety of colors within itself. Gregory submitted, “[T]he distinguishing individual traits shine on each in the commonality of the substance” (11). In other words, the inner works of the Trinity are distinguishable (but mutually entail one another) while the outer works are indivisible. Every action of God is sourced from the Father, executed by the Son, and completed in the Holy Spirit  (i.e. creation, salvation, and sanctification). In this way one cannot merely divide the actions of the Trinity from one another without dividing their persons beyond the point of heresy.

In accordance with God’s threeness, Gregory of Nyssa applies the term hypostasis, or person, and defines it as, “[N]ot the indefinite notion of the substance, which find no instantiation because of the commonality of what is signified, but that conception which through the manifest individualities gives stability and circumscription in a certain object to the common and uncircumscribed” (12). Put rather crudely, it is a particularity within the common substance which emphasizes the substance as a whole. These particularities are what the apostles and church fathers identified as the Father, Son, and Holy Spirit.

Despite these particularities, persons like Augustine of Hippo emphasized the strict equality between the three. He used the relationship between the mind, its knowledge, and its love as an analogy for the Trinity. He argued, “The mind therefore and its love and knowledge are three somethings, and these three are one thing, and when they are complete they are equal” (13). In other words, the mind cannot be different in substance from its love and its knowledge as they are closely intertwined by their very nature; however, these three are equal but not completely similar or else there would be no distinct three whatsoever. The mind, love, and knowledge are particularities which share the same reality. In the same way, the hypostases, or persons, of the Trinity are united in being, or essence (ousia), and action, yet there are particularities which distinguish the members from one another.

Constructing a Trinitarian model of God is by its very nature a lesson in theological boundaries. As the modalists and Arians demonstrated, heresy is merely a step too far in proclaiming either God’s oneness or threeness. Without both Scripture and the theological tradition which inherited it, a person is liable to venture this route. Therefore, Gregory of Nazianzus’s call for the selective use of theology only within certain limits and only through purified persons in body and soul (14) becomes not a call for intellectual elitism but rather for strict humility and rationality realizing that a person’s conclusions in such affairs are not from herself.


(1): Our term for the word, Trinity (or in Latin, trinitas), comes from Tertullian.

(2): Phillip Cary, “The Logic of Trinitarian Doctrine [Part I],” Religious and Theological Studies Fellowship Bulletin (Sept/Oct 1995): https://www.academia.edu/185279/The_Logic_of_Trinitarian_Doctrine (accessed 19 May 2019), 2.

(3): All Bible verses are from the English Standard Version.

(4): Arius, Arius’s Letter to Eusebius of Nicomedia, 5.1-5.

(5): Ibid., 5.6-8.

(6): Athanasius, “Orations Against the Arians,” in The Christological Controversy, ed. Richard A. Norris Jr. (Minneapolis, MN: Fortress Press, 1980), 71.

(7): Ibid., 70.

(8): Gregory of Nyssa, To Peter His Own Brother on the Divine Ousia and Hypostasis.

(9): Ibid.

(10): Ibid.

(11): Ibid.

(12): Ibid.

(13): Augustine, “Book IX: Psychological: Mental Image, First Draft,” in On the Trinity, 4.1-4.

(14): Gregory of Nazianzus, “An Introductory Sermon against the Eunomians,” in On God and Christ, trans. Frederick Williams and Lionel Wickham (Crestwood, NY: St Vladimir’s Seminary Press, 2002), 27.

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